public class circle extends Shape{
    public double r;

    public circle(double r) {
        this.r = r;
    }

    @Override
    public void S() {
        System.out.println("圆的面积："+ Math.PI * r * r);
    }

    @Override
    public void C() {
        System.out.println("圆的周长："+ Math.PI * r * 2);
    }
}
